There are mobile communication networks, wherein, in cases where there are few mobile stations located within a cell managed by a certain base station, or where the data communication volume of the mobile stations located within the cell is small, or the like, the base station changes to an Energy Saving State. The Energy Saving State is defined in the 3GPP technical specifications, and may be, for example, a state where several functions in the base station are halted, or where use of the resources in the base station is limited.
When a base station has been changed to an Energy Saving State, the coverage area of the cell managed by the base station is reduced. Therefore, the area which is no longer managed due to reduction of the cell coverage area as a result of change of the base station to an Energy Saving State is compensated for by increasing the coverage area of the cell of another base station. A state where the coverage area of the cell of one base station is used to compensate when another base station has changed to an Energy Saving State is called a “compensatingForEnergySaving state”. The compensatingForEnergySaving state is also defined in the 3GPP technical specifications.
Here, the changes in network configuration associated with a change of a base station to an Energy Saving State, as disclosed in Non-Patent Document 1, will be described with reference to FIGS. 13 and 14. FIG. 13 shows a case where base stations managing cell B to cell G have changed to an Energy Saving State, and the base station which is managing cell A is compensating for cell B to cell G. Here, a cell which is managed by a base station that has changed to the Energy Saving State is called an “energy saving cell” and a cell which is configured so as to compensate for an energy saving cell is called a “Compensation Cell”. In other words, cell A is a Compensation Cell, and cell B to cell G are energy saving cells.
Next, FIG. 14 shows a state where cell A becomes an energy saving cell due to the base station which manages cell A changing to an Energy Saving State. Moreover, FIG. 14 shows a case where cell B to cell G become Compensation Cells, due to the base stations which manage cell B to cell G compensating for cell A.